1. Field of the Invention
The present invention relates to a light-sensitive composition containing a fluorine-containing surfactant, and more specifically, to a light-sensitive composition capable of obtaining a light-sensitive layer of a uniform film thickness on a support.
2. Description of the Prior Art
Light-sensitive compositions have, in general, been used in a manner that they are coated on a support such as surface treated aluminum plates, paper, plastics or SiO.sub.2 /Si wafer in the form of solution or dispersion in an organic solvent and then are dried. When the light-sensitive compositions are coated on a support and then are dried, it is very important to form a light-sensitive layer of a uniform thickness on the support in order to sufficiently take advantage of the properties of the light-sensitive composition.
Heretofore, it has been quite difficult to obtain such a uniform light-sensitive layer in the drying process. According to a conventional process, the drying process comprises blowing air, having conditioned moisture and temperature, on a support coated with a light-sensitive composition to evaporate an organic solvent and form a light-sensitive layer. However, this drying process leads to the formation of non-uniform light-sensitive layer which has a non-uniform distribution of thickness due to the flow and turbulent flow of the air blown.
The unevenness of the thickness of the light-sensitive layer not only gives an unfavorable impression to its appearance but also results in inconsistant sensitivity and bad reproduction of the original pattern. Moreover, it leads to the lowering of printing durability and strength of image areas when the light-sensitive composition is used to form a printing plate.
In order to eliminate the unevenness of film thickness in the light-sensitive layer obtained after drying, it is necessary to carry out drying in a quite moderate manner. For this purpose, there have been proposed, for example, a method in which the velocity of air flow for drying is limited to a quite low value and the drying process is effected for an extremely long period of time, a method comprising utilizing air for drying having a temperature gradient, in which low temperature air is used in initial stages while high temperature air is sued in the final stage or a method in which an organic solvent having a relatively high boiling point is used in a larger amount to disperse and dissolve the light-sensitive composition. However, these methods cannot completely eliminate the unevenness of film thickness of the light-sensitive layer because of flowing air for drying and, in particular, in these methods a large and complicated installation for drying is needed since a web support is continuously conveyed to continuously coat it with a light-sensitive composition and continuously dry the coated composition, when manufacturing presensitized plates from which light-sensitive printing plates is to be prepared in an industrial scale. Moreover, if a specific solvent is selected and used, there is a serious drawback in that the selection of light-sensitive composition per se should be restricted within a narrow range.